DC9 FLC OVERFLIES THE DEST ARPT. SOME NAVAID PROBS.

Narrative

THE EVENT: A FLY-OVER OF GTF (GREAT FALLS; MT) WHILE ENRTE FROM MSP-GTF. WE OVERFLEW THE FIELD BY ABOUT 20-30 MI. THAT WAS OUR GREATEST DISTANCE FROM THE FIELD WHEN WE REALIZED OUR POS. HOW THE PROB AROSE AND CONTRIBUTING FACTORS: WE WERE GIVEN RADAR VECTORS SHORTLY AFTER TKOF FROM MSP DIRECT TO GTF WHEN ABLE. FLT WAS SMOOTH AT CRUISE. OUR LOCATION ALONG THE RTE WAS VERIFIED BY VOR XCHKS AND TIME. I PERSONALLY REALIZED THAT WE WERE CLOSE TO GTF BY OUR FLT TIME AND FLT PLAN BUT THERE WAS SOME QUESTION WITH OUR NAVAIDS -- WE WERE GETTING SOME CONFLICTING INDICATIONS. NO IDENT OF LEWISTON VOR -- ALSO ADDING TO CONFUSION WAS DME OTS AT GTF. ATC ALSO NEVER NOTIFIED US OF OUR POS. AS WE REALIZED OUR POS WITH ATC WE SIMPLY WERE GIVEN A DSCNT TO THE FIELD AND LANDED WITH NO PROBS. CONTRIBUTING TO THIS SIT WAS THE FACT IT WAS APCHING XX00 AM LCL TIME; WE SPENT 3.5 HRS DELAYED ON THE GND DUE TO A SNOW STORM IN MSP; WE WERE FLYING EARLY MORNING HRS WHILE ON DUTY FOR APPROX 12 HRS. OTHER FACTORS: UNFAMILIAR RTE. THE FACT THAT WE WERE GIVEN RADAR VECTORS; BUT NO INFO FROM ATC AS WE APCHED GTF. NO SIGNAL FROM LEWISTON AND LACK OF DME AT GTF. THE CONFUSION ACTUALLY OCCURRED BEFORE ARRIVING AT GTF; BUT BY THE TIME WE DSNDED WE WERE PAST GTF. THERE WAS NO CONFLICTS; OR ANY PROBS ON THE FLT; IT WAS UNEVENTFUL; OTHER THAN THE FACT WE OVERFLEW GTF. OUR CORRECTIVE ACTION WAS TO DSND TO THE FIELD AND LAND. SUPPLEMENTAL INFO FROM ACN 331337: WHEN AWARE THAT WE WERE AT LET DOWN TIME; WE HAD TROUBLE CONTACTING CTR WHEN WE FINALLY CONFIRMED STATION PASSAGE AND RECEIVED LET DOWN CLRNC WE HAD PASSED GTF.